Supporting pier



3 Sheets-Sheet l |nvenTon John R. Freeman ATTyS.

Feb. 7, 1928.

J. R. FREEMAN SUPPORTING PIER Filed Aug- 24. 1921 I 0 I u I n u n m n Feb. 7, 1928. 1,658,633

. J. R. FREEMAN SUPPORTING PIER File Aug. 24. 1921 s Sheets-Sheet 2 Fig. 5.

3o lnvenTor.

= John R, Freeman BYMMJIM 53 Aflys.

Patented 7, 1928.

warren srares JOHN R. FREEMAN, QF PROVIDENCE, RHODE ISLAND.

SUPPORTING PIER.

Application filed August 24, 1921. Serial No. 494.945.

This invention relates to the construction of a supportingpier particularly designed to be sunk in and rest upon soft earth, such as a deep bed of unstable soft river silt, and to support a structure such as a bridge.

One feature of the invention consists in such a pier provided with one or more cavities closed at the bottom and sides by the material of the pier and filled with substance, such as air or water, of less specific gravity than that of the earth supporting the pier, so that the specific gravity of the mass of the pier, considered as a whole, is reduced and a minimum amount of pressure at the base of the pier is exerted upon the earth.

The feature of the invention is thus to give a certain degree of buoyancy to the entire pier relatively to the surrounding soft earth, such as sand, clay, or silt, in which it is embedded and upon which it rests by means of a cavity within the pier partially or entirely filted with air or water or substance of less specific gravity than that of the earth. 7

The feature of the invention is to provide such a pier in which the size of the cavity and the amount and specific gravity of the filling substance have a proportional relation to the weight of the pier and its load and the area of the base and the character of the supporting earth such as to produce a pressure on the supporting earth at the base of the pier materially less than that which can be safelyborne thereby and not detrimentally greater than the normal pressure imposed by the surrounding earth the level of the base of the pier.

Other features of the invention reside in the means employed for reinforcing the pier when made of concrete, for provlding per-- manent rigid vertical columns in its exterior periphery to takeforces of thrust and draft and transmit them to the material of the pier during the sinking operation and tothe exterior configuration of thepier, by means of which, when it is sunk, the pressure of The drawings represent a supporting pier construction embodying a preferred form of the invention and particularly designed as a bridge pier to be formed of concrete and sunk in and supported by soft earth, such as alluvial soil or silt, often forming to a great depth the bed of a river at its delta.

In the. drawings:

Fig. 1 is a transverse vertical section of the completed pier in position.

Fig. 2 is a view on a larger scale taken on the line 22, indicating the high water level in Fig. 1.

Fig. 3 is a view on the same scale as Fig. 2 in transverse cross section taken on the line 33 of Fig. 1.

Fig. 4.- is an enlarged detail of one of the rigid vertical columns in transverse cross section taken on the line 4-4 of Fig. 5.

Fig. 5 is a view in vertical cross section of one of the columns taken on the line 5-5 of Fig. 4t.

Fig. 6 is a view in side elevation in partial vertical cross section, showing the metal reinforcement and cutting shoe at the bottom of the pier.

Fig. 7 is a view in vertical cross section partially broken away of the pier showing the relation of the reinforcing elements to the remainder of the structure.

'Fig. 8 is a front elevation of a portion of the structure shown in Fig. 6.

The pier embodying the invention is particularly designed as a monolithic shell of reinforced concrete having a large interior cavity, so that its body portion presents a caisson with a sharp lower peripheral cutting edge. The pier is-designed to be poured in successive layers prior to its sinking into the earth foundation and to be gradually sunk as a caisson. When it has been sunk to the required depth, the bottom of the shell is filled with a reinforced plug of concrete, which forms the base of the pier and which is interlocked with the shell of the pier.

A preferred apparatus and method for constructing and sinking such a pier or caisson is made the subject of Patent 1,630,337

granted May 31, 1927.

The body portion or shell of the pier which is embedded in the earth, such as the river bed. may take any desiredform, but is preferably as shown in Fig. 3 of a generally circular or polygonal shape. This ill:

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form presents the maximum resistance to the pressure of the surrounding earth with the minimum amount of material and is readily formed by the use of flat rectangular forms when the concrete is poured. The shape ot the pier structure above the river bed may also vary as desired. In the construction illustrated the annular shell 1 is exteriorly tapered upwardly, as shownat 2 in Fig. 2, and above the tapered portion is given a shape such as to give less obstruction to the current as shown at 3 in cross section in Fig. 2.

The large cavityd in the body or shell of the pier is preferably closed at the top by a transversewall or partition 5, in which manholes "6 are provided, and the section of the pier above this wall 5 is provided with suitable chambers 7 to reduce the weight of the pier. The partition b closes the cavity 4 below the low water level indicated a't 8-8 in Fig. 1, so that no frost strains can develop within the shell; and if necessary in cold climates the water in the cavity 4: may be kept even lower than this level. But the water may be allowed to rise and stand in the manholes at a higher level, because even in cold climates the thickness of the walls outside these manholes is so great that there is little danger from taper, which is of about one percent where the river bed is of silt or other similar for mation, is for the purpose-of reducing the skin friction of the surrounding earth when the pier is being sunk and is barely large enough to relieve the pressure of the surrounding earth, and admit the circulation of a thin film of water while sinking, but is not sufficiently large enough to invite any extensive inward movement of the earth while it is being sunk. This taper is inclicated in Fig. 1 by the vertical line 10-10.

The pier also embodies in its permanent construction a plurality of vertical water pipes 12, bent laterally at the bottom and provided with holes 13 at the exterior of the shell, through which water may be forcedand discharged to provide a lubrieating film when sinking with the pier. These pipes in the permanent construction of the pier provide a part of the vertical reinforcing means.

The main vertical reinforcement of the pier isprovided by a plurality of rigid vertical metal columns 14, preferably extendthe particular conditions. In the form illustrated there are sixteen, one at each of the angles of the exterior polygonal surface. A preferred form of these columns 18 1llustrated in detail in Figs. 4 and 5. Therein each column is shown as of channel form,

being made up of a vertical back plate 15 with two angle-irons 16 bolted tl1ereto, and presenting outwardly extending flanges 17 forming the channel. Each column may be made in vertical sections, as shown, and the abutting sections spliced together by the plate 18 andtheangle-irons 1S) boltedthereto. At frequent vertical intervals angleironsp20-are bolted to the rear of the column with their flanges projecting inwardly. The entire. "column with the inwardly projecting flanges of the angle-irons 20 is built into the concrete of the shell as it is poured and thus firmly embedded therein.

These rigid vertical columns thus present strong reinforcements to the material ol *the pier and serve to unite together into one mass thesuccessive layers or sections of concrete. lVhenthe pier is completed the channels of these columns are tilled with concrete "21, put in place as the shell is sunk into the earth.

These columns *not only serve as permanent reinforcements ot the :pier but they are also utilizable in transmitting forces of thrust and draft, preferably used in the sinking of the pier *as it is constructed. For this purpose each column is provided with a plurality of vertically separated steps, which form a permanent part of the pier. Each step, as illustrated. comprises a heavy iron bracket 22 bolted in place in the channel, as illustratcdin Figs. 4: and 5. This bracket comprises a heavy outwardly projectingstep23. These steps are designed to take on the top sur lt'ace at2 l the thrust from powerful jacks and on the bottom surface at25the pull or draft cxerted by extensible suspending means, such as heavy cable chains, all designed to assist in the speedy, accurate, and even sinking of the pier during its construction. and made the subject of the hereinbe tore mentioned patent. Thus these forces of thrust and draft are transmitted through vertical columns tothe lower sections of hard set concrete as the pier is sunk, and all danger of the shell of the pier being broken or cracked duringits sinking is prevented.

The pier is also suitably reinforced longitudinally and transversely whereverde sirable under the particular conditions by familiar means, such as twisted iron rods 26 embedded in the concrete at suitable points. A large number of these reinforcing rods are employed in circular transverse ill-3 I fill position in the shell of the pier and serve to reinforce the shell of the pier against any transverse or arch thrust.

The lower peripheral edge of the pier heavily reinforced, particularly for the purpose of supporting the sharp cutting metal shoe used in sinking, but this structure forms permanent part of the pier and is shown in detail in Fig. 6. This reinforcement comprises a plurality of generally tri angular frames. These frames are arranged radially of the shell of the pier and embedded in the lowermost section. Each is preferably bolted to and forms a continuation of one of the main vertical columns 1%. Une of the frames is shown in Fig. 6. It comprises a vertical angle-iron f2? and an inclined angle-iron 28, secured together by the transverse plates 29. These frames are faced at the lower, exterior with a metal plate 80 and at the lower interior with metal plates 31 and A heavy annular steel cut ting shoe 33 is bolted between the plates 30 and 31. The plates 36, 31, and 32 form a continuous annular reinforcement and surface for the extreme lower edge of the pier, as well as supporting the cutting shoe.

The pier is sunk by dr dging out the earth from the interior of the pier or caisson and utilizing the forces and means hereinbefore referred to. When the pier reaches the dcsired depth, it is closed at the bottom by a plug 34 of concrete, placed. in position by a tremie or open-bottom bucket and this forms the base of the pier. This plug is preferably reinforced by transversely arranged layers of separated bars 35 of railroad rails or other material, and it is interlocked with the shell of the pier by means of the grooves 36 formed in the interior periphery of the shell.

When the pier is completed and in posi tion, the cavity t is filled to any desired height, depending upon the particular con ditions, with a suitable filling substance, such air or water, or a ballast of sand or earth at the bottom in combination with air or water, so as to give the desired buoyancy to the pier. By varying the diameter and pro portioual size of the cavity and of the shell of the pier with relation to the area of the base and the particular character of, the supporting and surrounding earth and the amount and specific gravity of the filling substance and the total weight of the pier and its load, it is thus possible to cause the pressure produced by the pier and its load at the base on the foundation earth to be well within that which can be safely till borne by the earth at this point, even when of a soft and unstable nature. To. fact, this pressure is readily designed by this invention so as to be not detrimentally greater than the pre ll'G produced at the level of the base of t 1e pier by the sin-rounding earth itself. And when the shin f 'l'lml of the surrounding earth on the ei-dcrior periphery of the pier is considcred, no diillculty is experienced in bring ing the pressure at the base of the pier well within and below that which can be safely borne by the earth at this point. This means for producing a bouyancy of the pier and its lead with respect to the surrounding earth so as to enable it readily to be supported in soft earth, such as the silt or sand of a river bed, the important feature of the invention.

Having thus described my invention, what l claim as new and desire to secure by Letters Patent, is:

l. A. supporting pier embedded in and supported upon soft earth and provided with a cavity closed at the bottom and sides by the material of the pier and filled with water to a plane below low water level, whereby the pressure upon the supporting earth at the base of the pier may be brought within impossible limits and deleterious freezing of the water prevented.

2. A hollow supporting pier embedded in and supported upon soft earth and provided with a. cavity closed at the bottom and sides by the material of the pier and means for varying the pressure imposed upon the supporting earth by the pier and its load which consists in a filling substance placed within the cavity, in an amount and'of a specific gravity sullicient to secure the required sta bility and to make the pressure 011 the supporting earth at the base of the pier less than thatwhich can be safely borne by the supporting earth.

3. A hollow concrete supporting pier embodying a plurality of rigid vertical columns built into its exterior periphery and steps located atvertical intervals on the exterior of said columns utilizable to receive a vertical thrust or draft applied thereto and to transmit the same through the columns to the lower hard set concrete.

4-. A hollow concrete supporting pier to be sunk in soft earth having an exter1or upward and inward taper of approximately one per cent acting to relieve the inward pressure. and insufficient to invite the extensive inward movement, of the earth in which it is to be sunk.

5. A hollow concrete supporting pier embodying a plurality of rigid vertical columns built into its exterior periphery, a triangular metal frame secured to the bottom of each column and extending radially of the pier and embedded therein, and an an nular metal cutting shoe secured to the lower points of said frames.

6. rl hollow concrete supporting pier embodying a plurality of rigid vertical channel metal columns having secured to their rear plates horizontal vertically spaced projections, the said columnsbuilt into the exterior periphery of the pier with the channel faces outward and acting vertically to reinforce and unite the concrete of the pier into 5 a continuous mass.

7. A hollow concrete supporting pier having the construction defined in claim 6, to gether with a concrete filling in the channel faces of said columns.

8. A hollow concrete supportin pienhav- 111g the construction defined 311 c tum 6, together with metal steps sccuredat vertical intervals to said columns within the channel faces thereof.

In testimony whereof, I have signed my name to this specificatlon.

J OHN R. FREEMAN.

CERTWEGATE 0h CQRRECTHON.

Patent Ne. l,658,633. Granted Februaryi', 1928, to

.EXPHN R. FREEMAN.

It is hereby eefiiiied thei. en'm appears in the printed specification of the above numhered paten; requiring eorreetien as follows: Page 1, line 23, for the misspefled wen "fiited read "filled"; page 3, line 89, claim 1, for the word "impessibie" rea "impesabie"; and that the said Letters Patent should be read with these eerreetimae therein that the same may conform to the record of the ease fin ihe Patent (Hfiee.

Signed and sealed this 6th day 0% Mareh, A: D, F928,

M, J. Meme, Seal. Acting Commissioner of Patents. 

